It is known in the art that the blow molding operations depend upon the future utilizations of the container. For example, should the container be filled with a hot liquid (e.g. with drinks such as tea, pasteurized fruit juice, etc.), it is necessary to heat the mold in order to subject the container to a thermal treatment during the blow molding, thereby making it resistant to thermal shocks which will occur during the filling. Such a blow molding and the corresponding container are called “HR” (heat resistant) in the common terminology.
One drawback of such a method is that, by the end of the blow molding, the bottom of the container, which is still soft because of the thermal treatment, tends so stick to the mold bottom.
To overcome this problem, it is known to provide the mold bottom with a conduit which opens in the cavity in order to inject pressurized air into the cavity by the end of the blowing, thereby helping separation of the container from the mold.
However, this is not enough to allow for a quick separation of the container. Furthermore, there is a risk that pressurized air leaves a mark on the still soft container bottom, thereby locally weakening the container. In addition, such a mark happens to be unaesthetic.